1. Field of the Invention
The present invention relates to a steam-generating heating sheet for the eyes, which supplies modest heat and steam to the eyes and the area around the eyes in order to relieve eyestrain, alleviate dryness of the eyes, and provide a pleasant sensation.
2. Description of the Related Art
In the past, modest heat and steam was supplied to the eyes and around the eyes by using a steamed towel in order to relieve eyestrain and alleviate dryness of the eyes. Eye pillows have also been proposed, which make use of a steam-generating composition composed of a heat-generating material commonly referred to as a chemical pocket warmer, so that the user can supply modest heat and steam to and around the eyes easily and whenever necessary (Japanese Laid-Open Patent Applications 2001-170096 and 2001-245915 and elsewhere).
The eyes and the area around the eyes (particularly the thin skin of the eyelids) are very sensitive to heat, and the eyes are an organ that does not readily regenerate once damaged. If the steam released from a steam-generating composition is supplied directly to the eyes, there may occur a problem on safety because of the high temperature of the steam. Consequently, controlling the temperature of the steam released from the steam-generating composition is very important for an eye pillow that makes use of a steam-generating composition. In view of this, with conventional eye pillows that contained a steam-generating composition, in order to control the temperature of the steam supplied to the eyes, the steam-generating composition was housed in a moisture permeability pouch, after which a number of layers of nonwoven cloth, paper, or the like were laid over this as temperature buffers.
However, using several layers of temperature buffers made the eye pillow thicker and bulkier, and applying an eye pillow such as this over the eyes or around the eyes caused the wearer some discomfort because the pillow did not conform well to the unevenness around the eyes. Also, such eye pillows were more difficult to carry around, more inefficient to distribute for sale, and more expensive to manufacture. Another problem was that the paper or the like used as a temperature buffer would yellow during long-term storage, which diminished the commercial value of the product.
It is an object of the present invention to provide a steam-generating heating sheet for the eyes, which is thin thickness, can be manufactured inexpensively, and allows modest heat and steam to be supplied safely to the eyes and around the eyes.
The inventors have discovered that when a steam-generating composition is covered with a moisture-permeable sheet and steam is generated, if two or more moisture-permeable sheets are used on the steam generation side and the moisture permeability of these sheets is controlled so that a steam accumulation space is formed between the two moisture-permeable sheets, the steam can be kept at a temperature that is safe for the eyes, without using several layers of temperature buffer, and the steam temperature can be made more uniform so that the entire application surface is more evenly warmed, and therefore a steam-generating heating sheet for the eyes that is in the form of a thin sheet suited to application over the eyes and the area around the eyes can be produced at a low cost.
Specifically, the present invention provides a steam-generating heating sheet for the eyes, in which a steam-generating composition is contained, said steam-generating composition is covered with at least a first moisture-permeable sheet and a second moisture-permeable sheet in that order, and the steam-generating heating sheet for the eyes is stored in airtight container until use,
wherein the first moisture-permeable sheet has a moisture permeability (ASTM E-96-80D method) of at least 600 g/m2/24 hrs;
the second moisture-permeable sheet has a moisture permeability (ASTM E-96-80D method) of 700 to 3000 g/m2/24 hrs;
the first moisture-permeable sheet and the second moisture-permeable sheet are provided such that a steam accumulation space is formed therebetween; and
at least one of the moisture-permeable sheets covering the steam-generating composition has a water resistance of at least 400 mm.